Body shape

Line art depictions of a nude man and a woman designed to educate extraterrestrials about the appearance of the human body, from the Pioneer plaques. Notice broad shoulders of male and wide hips of female.

Human body shape has sophisticated details and purposes. Shape or figure is defined mainly by skeletal structure, muscles and fat^[1]. Skeletal structure grows and changes only up to when a human grows adult and remains same for rest of lifetime^[2]. During puberty differentiation of male and female body occurs for the purpose of reproduction. In an adult human muscle mass may change due to exercises and fat distribution may change due to hormone fluctuations. Inherited genes induce details of body shape.

Body shape has effects on body postures and gait, and plays major role in physical attraction between opposite sexes^[3]. This is because shape implies individual's hormone levels during his puberty which implies fertility, it also says about current levels of sex hormones^[4]. Good shape also implies good health and fitness of the body. Art of figure drawing defines body proportions that are considered as ideal.

Skeletal structure

Skeletal structure frames overall shape of the body. This remains almost the same in an adult human, and does not alter much during lifetime. Males are generally taller, but body shape is analyzed after normalizing normalizing with respect to height^[5].

Broad shoulders and expanded chest (in males): Widening of shoulders occur as part of male pubertal process^[6]. Expansion of ribcage is caused by effects of testosterone during puberty^[7]. Hence males generally have broad shoulders and expanded chest. This is to allow for more room to inhale more air for muscles. Wider shoulder results a swagger in shoulders while males walk^[8].

Male pelvis	Female pelvis
Comparison between a male (left) and a female pelvis (right).

Wide hips (in females): Widening of hip bones occur as part of the female pubertal process^[9]. Hence females generally have wide hips. This is to allow for child carrying and childbirth, the shape of a female pelvis is flatter, more rounded and proportionally larger to allow the head of the foetus to pass during childbirth^[10]. Estrogen causes widening of pelvis as a part of sexual differentiation. This affects their walking style, resulting in hip sway,^[11] also, females generally stand with hips relaxed to one side.

Facial features

Due to the action of testosterone, males develop these facial-bones features during puberty:

A more prominent brow bone^[12].
A squarer jaw.
Larger nose bone^[13].

Because females have around 20 times less testosterone, these features do not develop to the same extent, and smaller nose makes for fuller upper lip unlike males^[14]. Hence female faces are generally more similar to that of a pre-pubertal child.

Fat distribution and muscles

Body shape is affected by body fat distribution, which is correlated to current levels of sex hormones^[15]. Muscles and fat distribution may change from time to time, unlike bone structure, depending on food habits, exercises and hormone levels.

Fat distribution

Estrogen stores fat in the buttocks, thighs, and hips in women^[16]^[17]. When women reach menopause and the estrogen produced by ovaries reduces, fat migrates from their buttocks, hips and thighs to their waist^[18], later fat is stored in belly^[19]. Thus females generally have relatively narrow waist and big buttocks^[20], and this along with wide hips make for their bigger hip section and lower waist-hip ratio, around 0.7^{[citation needed]}.

Estrogens increases fat storage in the body^[21], which results more fat stored in body of females. Body fat percentage recommendations are more for females, this serves as an energy reserve for pregnancy. Males have less subcutaneous fat in face due to effect of testosterone^[22], also testosterone reduces fat by aiding fat metabolism. Males generally deposit fat around waist and abdomen("apple shape") due to lack of estrogen.

Muscles

Testosterone helps build and maintain muscles through weight exercise^[23]. Males have around 20 times more testosterone^[24]. Hence male body shape is cut and defined by muscles. It is difficult for females to develop muscles by exercises due to lack of adequate testosterone. Males generally resort to gym for keeping body fit. Even drugs are used to develop muscles. Prominent muscles of male body include biceps and triceps in arms and quadriceps of thighs.

Overweight and underweight

Overweight and underweight cause change in shape as well as posture and walking style. Obesity or overweight also brings about noticeable change in shape of body, obesity is measured using BMI or waist circumference. Depending on [BMI], body can be called as slim or fat or obese, exercises and diets are commonly used methods to keep it in acceptable range.

Clothing and accessories

Clothing or dresses enhances or even changes appearance of body. Fashion clothes enhance appearance of shape, while tight jeans, bikinis, bras, belts, corsets etc. hug body into their shape against gravity. High heeled sandals are generally used by females, alter body proportions.

Terminologies

Many terms or classifications are used to describe body shape. Classifications are mainly based on circumference of chest-waist-hip, like 36-24-36(inches).

V shape: Males have small bottom, bigger chest and wider shoulder, which makes for V-shape of torso. This is clearly seen in the likes of Superman.
Hourglass shape: Females body is significantly narrower in waist both in front view and profile view. Waist is narrower than chest region due to breasts and than hip region due to buttocks, which resembles an hourglass.
Apple: Belly region is bigger than hip section, mainly males.
Pear or spoon or bell: Hip section bigger than upper body, mainly females^[25].
Rectangle or straight or banana: Hip section, waist and shoulder are straight.

Notes

^ body shape is determined by the nature of body fat distribution [1]
^ Growing is usually completed between ages 13 and 18, at which time the epiphyseal plates of long bones close allowing no further growth - Human skeleton
^ body shape is important in physical attraction [2]
^ "body shape is determined by the nature of body fat distribution that, in turn, is significantly correlated with women's sex hormone profile, risk for disease, and reproductive capability" [3]
^ Males are taller
^ Secondary sexual characteristics occur as part of the pubertal process. [4]
^ testosterone causes expansion of rib cage during puberty as one of secondary sex characteristics.[5]
^ males walk with swagger in shoulders [6]
^ Secondary sexual characteristics occur as part of the pubertal process. [7]
^ see Gender differences in Human skeleton and Sexual dimorphism in Hips
^ females walk with hip sway [8]
^ bone across the centre of the forehead from around the middle of eyebrow across to the middle of the other
^ testosterone thickens the brow and "upper bridge of the nose" [9]
^ Females have fuller lips. [10]
^ "body shape is determined by the nature of body fat distribution that, in turn, is significantly correlated with women's sex hormone profile" [11]
^ estrogen causes fat to be stored around the pelvic region, hips, butt and thighs [12]
^ [13]
^ Researchers think that the lack of estrogen at menopause play a role in driving our fat northward [14]
^ Abdominal fat and what to do about it [15]
^ "Big butts are back"article Cosmopolitan
^ estrogen women have activates fat storing enzymes and causes them to multiply [16]
^ "Subcutaneous fat in face decreases" - Advanced postnatal effects
^ Maintaining sufficient levels of the hormone testosterone can "build muscle and decrease body fat" [17]
^ On average, overall men have about "20 times more testosterone than women" [18]
^ Illustration of shape in body shape calculator. [19]

[1] y shape is determined by the nature of body fat distribution [1]

[2] Growing is usually completed between ages 13 and 18, at which time the epiphyseal plates of long bones close allowing no further growth - Human skeleton

[3] y shape is important in physical attraction [2]

[4] "body shape is determined by the nature of body fat distribution that, in turn, is significantly correlated with women's sex hormone profile, risk for disease, and reproductive capability" [3]

[5] Males are taller

[6] Secondary sexual characteristics occur as part of the pubertal process. [4]

[7] testosterone causes expansion of rib cage during puberty as one of secondary sex characteristics.[5]

[8] s walk with swagger in shoulders [6]

[9] Secondary sexual characteristics occur as part of the pubertal process. [7]

[10] see Gender differences in Human skeleton and Sexual dimorphism in Hips

[11] s walk with hip sway [8]

[12] ross the centre of the forehead from around the middle of eyebrow across to the middle of the other

[13] testosterone thickens the brow and "upper bridge of the nose" [9]

[14] Females have fuller lips. [10]

[15] "body shape is determined by the nature of body fat distribution that, in turn, is significantly correlated with women's sex hormone profile" [11]

[16] strogen causes fat to be stored around the pelvic region, hips, butt and thighs [12]

[17] [13]

[18] Researchers think that the lack of estrogen at menopause play a role in driving our fat northward [14]

[19] Abdominal fat and what to do about it [15]

[20] "Big butts are back"article Cosmopolitan

[21] strogen women have activates fat storing enzymes and causes them to multiply [16]

[22] "Subcutaneous fat in face decreases" - Advanced postnatal effects

[23] Maintaining sufficient levels of the hormone testosterone can "build muscle and decrease body fat" [17]

[24] On average, overall men have about "20 times more testosterone than women" [18]

[25] Illustration of shape in body shape calculator. [19]

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